Schools in low-income urban communities present a context with great potential for the implementation of psychosocial evidence-based practices (EBPs). Cognitive-behavioral therapy (CBT) is an EBP that has been found to be very effective in treating anxiety in various community settings, including schools. Friends for Life (FRIENDS) are an efficacious group CBT protocol for anxiety. Unfortunately, EBPs for anxiety are seldom employed in under-resourced urban schools, because treatment protocols are not tailored to the context or the population, existing behavioral health staff does not receive adequate training or support to allow them to implement the treatment with fidelity, and school districts do not have the resources to contract outside providers or consultants. In our prior work, we developed a more culturally sensitive, focused, and feasible CBT for anxiety protocol (adapted FRIENDS). The adapted protocol (aFRIENDS) addresses one of the major barriers to implementation (intervention context fit). Community mental health agency therapists who provide services in schools usually receive some training in EBPs but typically lack access to adequate support, such as clinical supervision, which is necessary for maintaining treatment fidelity. Two important questions regarding dissemination and implementation (D&I) of EBPs are: a) Can publicly funded mental health therapists in urban schools successfully implement EBPs when supported by their own agencies or does successful implementation require external, expert support? b) What is the comparative cost effectiveness of these two different implementation strategies? The aim of this five-year study is to conduct a 3-arm, parallel group, Type 2 hybrid effectiveness- implementation trial in 18 K-8 schools. Therapists and supervisors will be randomly assigned to one of three conditions: a) FRIENDS with Train-the-Trainer implementation strategy (i.e., Masters-level supervisors receive training from experts on conducting supervision); b) aFRIENDS with Train-the-Trainer strategy; c) aFRIENDS with Train-the-Trainer Plus strategy (i.e., supervisors receive training and consultation from experts on conducting supervision). We will also assess cost-effectiveness and mediators and moderators of implementation strategies on fidelity. Ninety therapists (30 per arm), 18 agency supervisors (6 per arm) and 360 children (120 per arm) will participate. Our guiding framework is the Interactive Systems Framework for Dissemination and Implementation. Therapists and supervisors will use GoToMeeting and SIMULATIONiQ Counseling TM, a cloud-based, HIPAA- compliant system for training mental health workers.